Deion tube



Nov. 4, 1952 R. D. HANCOCK DEION TUBE Filed March 9, 1951 649 ,4r LOW M60/m05 #2655026 Patented Nov. 4, 1952 DEON TUBE Robert D. Hancock, Compton, Calif., assigner 'to Northrop Aircraft,l Inc., Hawthorne, Calif. a corporation of California Application March 9, 1951, serial ria/2514383 1 Claim. l My invention relates to lthree electrode cold cathode glow tubes, and, more particularly, toa means and method of increasing operating rate of a cathode glow tube when used as a switch or flip-'flop by ion control. Tubes incorporating the invention are particularly suitable for useascomponents in high speed binary counters.

ThisA invention is an improvement on the tube shown,- described and claimed vin the Hagen -application, Serial No. 100,178, led June 6, 1949.

In the manufacture of cold cathode glow tubes of the Hagen type, it has been found that when the tubes are made extremely small so that the envelope walls are close to the electrodes, sput- `tered metal from the electrodes, after a period of operation, will coat the walls and, by ion entrapment, build up a charge that greatly reduces the deionization time of the glow in the tube, thereby increasing the rate at which the tube will operate. At a certain point in the life of such a tube, the operational rate of the tube has been found to be increased by a factor of two, for example. However, such small tubes contain very little gas and their life is short due to the gas clean-up by the sputtering. In addition, the period of optimum condition of the sputtered coating for high operational rates is very short and is passed through as the tube ages. It is an object of the present invention to provide a cold cathode glow tube having a constant high operational rate by virtue of controlled ion removal, and which will, at the same time, have a relatively long useful life at such operational rates.

In brief, the present invention places the three electrodes of the Hagen tube inside of a relatively close fitting gas permeable conductive ion collector, preferably maintained at a potential less than that imposed between anode and cathodes. The ion collector and enclosed electrodes are then placed inside of a relatively large envelope filled with an inert gas such as neon at glow discharge pressure, one-half atmosphere for example. The ion removal from the glow discharge areas decreases deionization time and operation rates are thereby a factor of about two or better. The large gas volume insures a long useful life, in spite of sputter clean-up. The end result is a stable high rate cold cathode glow tube with a relatively long life, eminently suitable for use in flip-nop circuits as incorporated in binary counters.

My invention can be more fully understood by reference to the drawings in which:

Figure 1 is a side elevational view, with the envelope partly removed. of a three electrode glow tube embodying the present invention.

Figure 2 is a circuit diagram showing the tube of Figure 1 as used as a switch or ip-op.

Referring rst to Figure 1, an envelope I is provided at one end with an exterior pinch seal 2 supporting-three small parallel glass `tubes. Y 'e Ycentral tube f3 encloses an anode wire 4and vthe `an anode I0 and two cathodes 1I2 and 13.

A metal plate I4 is sealed to the inner ends-of the three glass tubes v3, "5 and 6 -adjacentthe exposed anode I D and cathodes I2 and I3, this plate I4 being provided with a plurality of gas holes I5. A cup shaped meta1 cover I6 is then placed over plate I4 to form a conductive enclosure close to and around anode III and cathodes I2 and I3. An exterior lead I'I is connected to cover I6 and is brought out of the envelope through a lead seal I8 at the end of the tube opposite pinch 2. The tube is filled with gas such as neon at from 100 mm. to one-half atmosphere, for example, with a trace of polyatomie gas therein to increase deionization time, as disclosed in the Hagen application cited above.

In operation, one way in which the tube can be operated is shown in Figure 2. Here, the anode II! is connected to a pulse input line 20 and through a limiting resistor 2| to one end (positive) of a potentiometer resistance 22 bridged by a potential source such as battery 23.

The opposite (negative) end of resistance 22 and battery 23 is grounded.

Each cathode I2 and I3 is connected to ground through a cathode resistance 24 bridged by a capacity 25, and an output line 26 can be connected to each cathode I2 and I3.

When the anode is energized to a voltage where a glow discharge can strike in the tube, this glow discharge will strike between one only of the cathodes and the anode. Thereafter, when a pulse is applied tothe anode I 0 through input line 20, the glow discharge will be switched to the other cathode, a switch from one cathode to the other being made for every input pulse applied. Placed in cascade, such tubes can be used in binary counters in place of the well known three electrode vacuum tubes.

As it is highly desirable that the deionization time of the tube be as short as possible in order that high counting rates be attained and maintained, I attach the enclosure lead I'l to potentiometer resistance 22, preferably through a variable contact 21, so that the potential on enclosure I4, I6 can be varied to obtain maximum switching rates by ion collection. In most instances, an increase in switching rate by a factor of two or better is provided by the use of the controlled voltage enclosure, over that obtainable in a similar tube used without any enclosure. This potential, however, will not be sufficient at any time to cause a glow discharge to strike to the enclosure i4, I6.

As gas is entrapped by sputtering inside of enclosure I4, I6, the large supply in the envelope Il, through holes I5, replenishes the enclosure, and prevents any rapid change in pressure, with a resulting long life of the tube.

It will be seen from the above description that the advantages' of high switching rate and long life have been provided in the tube of the present invention.

While in order to comply with the statute, the invention has been described in language more or less specic as to structural features, it is to be understood that the invention is not limited to the specific features shown, but that the means and construction herein disclosed comprise a preferred form of putting the invention into effect, and the invention is, therefore, claimed in any of its forms or modifications Within the legitimate and valid scope of the appended claim.

What is claimed is:

A cold cathode glow tube comprising an envelope lled with a gas at cathode glow discharge pressure, three coplanar side-by-side electrodes to form an enclosure for said tips, said enclosure having apertures therein to permit gas from said envelope to enter said enclosure, the volume of said envelope being substantially greater than the volume of said enclosure, and an exterior lead for' said enclosure.

ROBERT D. HANCOCK.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,789,626 Hendry Jan. 29, 1931 1,886,180 Green Nov. 1, 1932 1,984,469 Ewest Dec. 18, 1934 2,338,837 Clack et al Jan. 11, 1944 2,451,556 Holdaway Oct. 19, 1948 

